Three beam gun



July 31, 1956 c. H. JONES ETAL THREE BEAM GUN Filed July 30. 1952 INVENTORS Charles H. Jones and Chester P Carpenter Z W ATTORNEY WITNESSES. W K

2,757,301 1 n BEAM GUN Charles H. Jones and Chester P. fiarpenter, Pittsburgh, Pa., .assignors to Westinghouse Electric Corporation, 'East'Pittsburgh, Pa., a corporation of Pennsylvania Application July 30, 1952, Serial No. 301,706

9 Claims. (Cl. 313-" 6) Our invention relates to a new type of electron gun and more particularly to a three beam "kinescopes.

In accordance with the prior art, of which we are aware, where it is desired in a color television tube to employ threedistinct beams for scanning purposes, three independent electron guns have been provided. By employing three independent guns, substantial expense is incurred in producing the required electrodes, which would not-be incurred if some of the elements'of the guns were common to all three guns.

It is, therefore, an object of our invention to produce an electron gun having a single cathode and focusing electrodes capable of producing three beams which can be independently modulated. I Another object of our invention ,is to provide a three beam electron gun which produces three beams which can be accurately spaced in cross sectional distances apart. Another object of our invention is to provide means for producing three independent beams of electrons in Y -Tl1e invention with respect to both the organization and the operation thereof, together-with other objects and advantages may be best understood from the following description of specific embodiments when read in connection with the accompanying drawing, in which:

Figure 1 is a schematic showing in cross section of a cathode ray tube built in accordance with one embodiment of our invention.

Fig. 2 is a cross section'of the television tube shown in Fig. 1, taken along the line HII of Fig. 1 so as to show the cross section of the ratio section.

Fig. 3 is a cross section of the apparatus shown in Fig. 1, taken along the line Ill-III of Fig. 1 so as to show a cross section of the beam splitting section.

Fig. 4is a cross section of the apparatus shown in Fig. 1, taken along the line IVIV so as to show a cross section of the beam positioning section.

In accordance with our invention, we provide an evacuated envelope 6 preferably of a dielectric material such as glass. This envelope is provided with a large end 8 on the inside of which maybe coated a fluorescent material 10 which produces light when electrons impinge thereon. screen 12 on which an imageis produced which may be viewed by an observer. In the opposite end of the tube from the screen 12 there is provided a cathode14 and a plurality of accelerating and focusing electrodes 16, 18,

20. The accelerating and focusing electrodes 16, 18, 20

produce a beam of electrons of small cross section and The fluorescent material 10 comprises the gun for color project that beam down the axis of the tube toward the screen 12.

Between the accelerating electrodes 16, 18, 2t) and the screen 12 there are three sections designed to separate the electron beam into three parts .and to control the intensity of each of the three parts independently. A first of these sections, which is the one closest the accelerating electrodes, 16, 18, 20 we shall call the ratio section 22. The ratio section comprises three plates 23, 24, 25 arranged substantially in the form of a triangle or delta, as is shown in Fig. 2. The three plates 23, 24, 25 of the ratio section 22 are arranged so that the center of their cross sectional triangle lies on the axis of the tube. The three plates 23, 24, 25 of the ratio section 22 are electrically insulated from each other and are provided with connections 27 for applying variable high frequency potentials to those plates independently of each other.

Adjacent to the ratio section 22 and substantially coaxial therewith, is a beam splitting section 26. The beam splitting section comprises a center section 28 which comprises essentially three plates which extend parallel to the axis of the tube and the cross section of which, when taken across the tube, is in the form of a Y. The three plates comprising the center section 28 of the beam splitting section are connected together electrically at the axis of the tube. Connections 29 are provided for applying a small clirectrcurrent potential to the beam splitting section.

Adjacent the beam splitting section 26 and coaxial therewith is .a positioning section 3%). The positioning section 30 comprises six plates extending parallel to the axis'of the tube. Three of the sir plates of the positioning section 30 are arranged in a triangle 32 in themanner ofthe ratio section. The other three plates or thepositioning section are arranged cross sectionally in the form of a Y 34 similar tothe arrangement of the beam splitting section. The three Y plates 34 in the positioning section 30 which are arranged in cross section in the form of a Y are located inside the three delta plates 32 which are arranged in cross section in the form of a delta or triangle. V

In 'accordance'with one embodiment of my invention, the Y section 28 of the ratiosection could be a physical extension of the 'Y section 34- of the positioning section and the two Y sections 28, 34- would be at the same potential. Connections 36 are supplied for providing variable directcurrent potentials to the three delta plates of the positioning section so as to vary the potentials on the three delta plates independently. The three Y plates 34 in'the positioning section, which are electrically connected together, are provided with connections 38 for applying a direct-current potential thereto in a manner'sirnilar to that employed in the beam splitting section 26.

'We thus have a ratio section 22, the cross section of which is in the form of a delta, a beam splitting section 26, the cross section of which'is in the form of a 'Y, and a'positioningsection 30, the cross section of which includesboth'a delta section and a Y section.

In the region of the beam positioning section '30, there is provided a convergence coil 39. The convergence coil 39 is adapted to produce a field which will cause the three beams to again proceed in a direction parallelto the axis of the tube after leaving the beam splitting section 26.

Between the beam positioning section 30 and the fluorescent screen lltl, there are provided a plurality of deflection'electrodes ill, the use and configuration of which are well known in the art. f course, as will be readily apparent to one skilled in the art, deflection coils might be employed in lieu of deflection electrodes.

In the operation of theembodiment of our invention shown in the drawing, electrons are emitted from the cathode 14. These electrons are accelerated and formed into a beam of small cross section by the three accelerating electrodes 16, 18, 20. This portion of the apparatus. is built in accordance with principles well known in the: art.

When the electron beam emerges from the accelerating electrodes 16, 18, 20 it passes into the region of the ratio section 22. There the beam is deflected toward the plate of the ratio section 22 which is the more positive. Theratio section 22 thus determines in what ratio the beam will be split.

When the beam emerges from the ratio section 22, its axis is slightly displaced from the axis of the tube. When the beam passes into the delta section or beam splitting section 26 the electrons of the beam, which are divided among the three regions separated by the plates 28, are deflected outward away from the axis of the tube. Since the axis of the beam has been deflected from the axis of the tube before the electrons reach the beam splitting section, more of the electrons will be in one of the regions separated by the plates 28 than will be in a region between other of the plates. The relative distribution depends, of course, upon the potentials which have been applied in the ratio section 22.

After the beam has been split in the beam splitting section 26, the electron beams formed by the beam splitting section pass into the positioning section 30. The potential of each of the three outer plates 32 of the positioning section is made positive with respect to the three inner plates 34. The greater the potential on the outer plates with respect to the inner plates the greater will be the separation of the three beams as they emerge from the positioning section 30. Thus, the position of each beam with respect to the axis of the tube can be independently adjusted in the positioning section 30 by the application of a suitable voltage to the outer plate 32 associated with it. 7

Although we have shown and described specific embodiments of our invention, we are aware that other modifications thereof are possible. Our invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and the spirit of the invention.

We claim as our invention:

1. A color television tube comprising in the order named means for producing a primary electron beam, means for deflecting said primary electron beam, means for splitting said primary electron beam into a plurality of secondary electron beams, means for positioning each of said secondary electron beams and means for converging said secondary electron beams.

2. A cathode ray tube comprising an envelope and having therein means for producing a primary electron beam, planar separating electrodes parallel to said primary electron beam for separating said electron beam into three secondary electron beams, positioning elec trodes for positioning said three secondary electron beams independently, and deflection means positioned between said electron producing means and said separating electrodes for deflecting said primary electron beam to vary the number of electrons in each of said secondary electron beams.

3. A beam separating apparatus for use in a cathode ray tube comprising three sections aligned with a common axis; a first of said sections comprising three plates arranged substantially in the form of a triangle and electrically insulated from each other; a second of said sections comprising three plates arranged substantially in a cross section configuration of a Y and connected electrically together; and a third of said sections comprising three plates arranged so that their cross section forms substantially a triangle and insulated from each other, and three plates electrically connected together located inside the region which is partially enclosed by said last r 4 mentioned three plates so as to form in cross section a Y. i

4. A cathode ray tube comprising an envelope and having therein in the order named, electrodes for producing a beam of electrons, deflection electrodes for deflecting said beam, planar separating electrodes parallel to said electron beam for separating the electron beam produced by said electrodes into three beams, and positioning electrodes for positioning said three beams independently. i

5. A cathode ray tube comprising an envelope and having therein in the order named, an electron emitter, zaeceleration electrodes disposed to accelerate electrons iemitted by said emitter, focusing electrodes disposed to focus said electronsso as to form an electron beam, deflection electrodes for deflecting said beam, separating electrodes for impressing accelerations on part of the electrons in said beam in a direction lying in a cross sectional plane of said beam, and positioning electrodes disposed to position the electrons accelerated by said separating electrodes independently of the other electrons in said beam.

6. Beam splitting apparatus comprising: three sections aligned with a common axis; a first of said sections comprising three plates parallel to said axis arranged substantially in the form of a triangle and electrically insullated from each other; a second of said sections comprising three plates parallel to said axis arranged substantially in a cross section configuration of a Y and connected electrically together; and a third of said sections comprising three plates parallel to said axis arranged so that their cross section forms substantially a triangle and electrically insulated from each other, and three plates parallel to said axislocated inside the region which is partially enclosed by said last-mentioned three plates so as to form in cross section a Y and being electrically connected together.

7. A color televisiontube comprising an electron gun for generating an electron beam along a normal path, a screen positioned transversely to said electron beam, a first means positioned between said electron gun and said screen for producing a beam deflecting field transversely to said electric beam path, a second means positioned between said first means and said screen for splitting said electron beam into individual parts, a third means cooperating with said second means positioned between said second means and said image screen for individual positioning each of said electron beam parts, a fourth means positioned in the region of said third means for converging said electron beam parts, and a fifth means for deflecting said electron beam parts to scan rasters on said image screen.

8. A color television tube comprising an electron gun for projecting an electron beam along a normal path, an image screen positioned transversely to said electron beam, a first set of electrodes positioned between said electron gun and said image screen for displacing said electron beam from said normal path, a second set of electrodes positionedbetween said first set of electrodes and said image screen for dividing said electron beam into individual parts, a third set of electrodes positioned between said second set of electrodes and said image screen for individually positioning each of said electron beam parts, and a fourth set of electrodes for deflecting said electron beam parts as a unit so as to scan a raster on said image screen.

9. A color television tube comprising an envelope and having therein an electron gun for producing a single electron beam along a normal path, an image screen positioned transversely to said single electron beam, means positioned between said electron gun and said image screen for producing a beam deflecting field transversely to said single electron beam path, a beam splitting structure positioning. between said beam deflecting field means References Cited in the file of this patent UNITED STATES PATENTS 2,252,744 Fleming Williams Aug. 19, 1941 Shelton et a1. Dec. 14, De Gier Feb. 15, Adler May 22, Schade June 12, Donal Aug. 21, Jenny Jan. 8, Sziklai Feb. 22, Labin Aug. 19, Jenny Sept. 16, Friend Apr. 7, Skellett June 14,

FOREIGN PATENTS Great Britain Sept. 15, France June 16,

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